Ferrous Oxalate Dihydrate Research Articles

Synthesis of Alpha Ferrous Oxalate Dihydrate from Ferrotitaniferous Mineral Sands via Hot Pressurized Aqueous Oxalic Acid: Kinetics and Characterization

Ferrous oxalate dihydrate is a versatile organic mineral with applications across fields. However, little is known about the feasibility of its synthesis directly from iron-bearing minerals using binary subcritical water (sCW) systems and its associated kinetics. In this study, the sCW+oxalic acid system at either 115 °C or 135 °C was investigated as a reaction medium for ferrous oxalate dihydrate (α-FeC2O4∙2H2O) synthesis, starting from ferrotitaniferous sands. The kinetics of the synthesis reaction were studied, and the physicochemical characterization of the as-synthetized ferrous oxalates was performed. Overall, the sCW synthesis was temperature-dependent, following second-order reaction kinetics according to the proposed precipitation pathway. A high reaction rate constant, significantly high yields (up to 89%), and reduced reaction times (2–8 h) were evident at 135 °C. The as-synthetized product corresponded to the monoclinic α-FeC2O4∙2H2O, showed relatively high specific surface areas (from 31.9 to 33.7 m2∙g−1), and exhibited band gap energies within the visible light range (~2.77 eV). These results suggest that α-FeC2O4∙2H2O can be synthesized using an organic dicarboxylic acid and iron-rich, widely available, low-cost mineral precursors. In addition, the as-prepared α-FeC2O4∙2H2O could be further optimized and tested for catalytic and visible light photocatalytic applications.

Regulation of Ethanol on Ferrous Oxalate Particle Size and Properties: Theoretical and Experimental Study

AbstractSurfactants containing hydroxyl functional groups have a significant influence on the morphology of ferrous oxalate dihydrate. However, few studies have provided a theoretical explanation for this effect. In this investigation, the size of ferrous oxalate dihydrate was reduced from micron to nanometer scale using anhydrous ethanol, and its mechanism was elucidated through density functional theory calculations. The calculational results reveal that anhydrous ethanol molecules bound to the ferrous oxalate dihydrate crystal via hydrogen bonding and van der Waals forces, thereby controlling crystal growth. It means that anhydrous ethanol molecules preferentially affected the interlayer interaction in the structure of ferrous oxalate dihydrate, leading to a significant impact on its overall crystal growth way. Furthermore, the electrochemical properties of ferrous oxalate dihydrate synthesized in aqueous and anhydrous ethanol systems were compared and tested. The specific capacitance (242 F ⋅ g−1 at 0.5 A ⋅ g−1 current density) of ferrous oxalate dihydrate synthesized in anhydrous ethanol system is obvious higher than that of ferrous oxalate dihydrate synthesized in water system (186 F ⋅ g−1), due to its smaller particle size (75 nm). Furthermore, the specific capacitance of this material can be improved to 469 F ⋅ g−1 during composite process of ferrous oxalate dihydrate with graphene oxide.

Synthesis of submicron ferrous oxalate from red mud with high Fenton catalytic performance on degradation of methylene blue.

Ferrous oxalate dihydrate (FOD) can be used as a photo-Fenton catalyst with remarkable photo-Fenton catalytic and photocatalytic performances on organic pollutant degradation. Various reduction processes were compared in the current study to synthesize FODs from ferric oxalate solutionutilizing the iron source in alumina waste red mud (RM), including natural light exposure (NL-FOD), UV light irradiation (UV-FOD), and hydroxylamine hydrochloride hydrothermal method (HA-FOD). The FODs were characterized and employed as photo-Fenton catalysts for methylene blue (MB) degradation, and the effects of HA-FOD dosage, H2O2 dosage, MB concentration, and the initial pH were investigated. The results show that HA-FOD has submicron sizes and lower impurity contents with more rapid degradation rates and higher degradation efficiencies compared with the other two FOD products. When using 0.1g/L of each obtained FOD, 50mg/L of MB can be rapidly degraded by HA-FOD by 97.64% within 10min with 20mg/L of H2O2 at pH of 5.0, while NL-FOD and UV-FOD achieve 95.52% in 30min and 96.72% in 15min at the same conditions, respectively. Meanwhile, HA-FOD exhibits strong cyclic stability after two recycling experiments. Scavenger experiments reveal that the predominant reactive oxygen species responsible for MB degradation are hydroxyl radicals. These findings demonstrate that submicron FOD catalyst can be synthesized using hydroxylamine hydrochloride hydrothermal process from ferric oxalate solution with high photo-Fenton degradation efficiency and reduced reaction time for wastewater treatment. The study also provides a new pathway of efficient utilization for RM.

Spatial analysis of CO2 hydrogenation to higher hydrocarbons over alkali-metal promoted iron(ii)oxalate-derived catalysts

The kind of alkali metal in ferrous oxalate dihydrate affect the concentration and spatial distribution of iron carbides formed in situ in CO2 hydrogenation. These structural changes impact the rate of CH4 formation from CO2 but not from CO.

Microspheres of Ferrous Oxalate Dihydrate: Formation, Structure, Physical Properties, and Photocatalytic Activities

Microspheres of Ferrous Oxalate Dihydrate: Formation, Structure, Physical Properties, and Photocatalytic Activities

A Study of the Mechanism of Particle Size Control of Ferrous Oxalate Dihydrate by N,N-Diethylacetamide

A Study of the Mechanism of Particle Size Control of Ferrous Oxalate Dihydrate by N,N-Diethylacetamide

Anodic Activity of Hydrated and Anhydrous Iron (II) Oxalate in Li-Ion Batteries

We discuss the applicability of the naturally occurring compound Ferrous Oxalate Dihydrate (FOD) (FeC2O4·2H2O) as an anode material in Li-ion batteries. Using first-principles modeling, we evaluate the electrochemical activity of FOD and demonstrate how its structural water content affects the intercalation reaction and contributes to its performance. We show that both Li0 and Li+ intercalation in FOD yields similar results. Our analysis indicates that fully dehydrated ferrous oxalate is a more promising anodic material with higher electrochemical stability: it carries 20% higher theoretical Li storage capacity and a lower voltage (0.68 V at the PBE/cc-pVDZ level), compared to its hydrated (2.29 V) or partially hydrated (1.43 V) counterparts.

Thermal decomposition of ferrous oxalate nanowires to porous nanowire-like α-Fe2O3 with a good gas-sensing properties

This research was performed to study a convenient, surfactant free and reducing approach for the synthesis of ferrous oxalate dihydrate (FeC2O4·2H2O) nanowires with a large aspect ratio using Fe(III) ions as iron source and ethylene glycol (EG) as reducing agent. X-ray diffraction, scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and thermal gravimetric analysis were utilized to reveal the structures. After calcination, mesoporous nanowire-like α-Fe2O3 with a large aspect ratio were prepared, which presents a good gas-sensing characteristics. The sensor response to 100 ppm ethanol was 25.7, combined with very short response and the recovery times at a working temperature of 240 °C. Furthermore, the obtained nanowire-like α-Fe2O3 sensor also exhibited a good long-term stability. The good properties were related the high content of the defect related oxygen species which revealed by the X-ray photoelectron spectroscopy.

Preparation of Magnetite by Thermally Induced Decomposition of Ferrous Oxalate Dihydrate in the Combined Atmosphere

This study presents an investigation of thermal decomposition of ferrous oxalate dihydrate in the combined atmosphere of inert and conversion gases to find an optimal route for a simple magnetite preparation. Homogenized precursor was isothermally treated inside the stainless-steel cells at 8 equidistant temperatures ranging from 300 to 650 °C for 1, 6, and 12 hours. The enclosure of samples inside the cells with the combined atmosphere eliminates the necessity of the inert gas to flow over the treated samples. Structural, magnetic, and morphological aspects of the prepared materials were examined by the combination of experimental techniques, such as Mössbauer spectroscopy, X-ray powder diffraction, and scanning electron microscopy.

Purification of high iron wet-process phosphoric acid via oxalate precipitation method

A method has been developed to reduce the iron content in phosphoric acid produced by the dihydrate wet process from open cast phosphate rock of Abu-Tartur mine in Egypt. In this method, oxalic acid was used to precipitate iron as ferrous oxalate dihydrate (FeC2O4.2H2O). The achieved removal efficiency of iron was about 91% due to the low solubility of the precipitated salt in dilute phosphoric acid medium. The maximum P2O5 losses were less than 1.0%. The optimum conditions of oxalate precipitation method were obtained using synthetic dilute phosphoric acid (28% P2O5, 390 g/L H3PO4) with iron content amounting 2.8% (w/w) Fe2O3 (26.3 g/L Fe). It was found that, the clarification time, reaction temperature, P2O5 concentration and oxalic acid dose were 2 h, 60 °C, 28% P2O5 and 7.5 g oxalic acid/100 g 28% P2O5 acid, respectively. These conditions were applied using wet-process phosphoric acid (26% P2O5). Firstly, ferric ions in the acid were reduced to ferrous ions using iron scrap, followed by oxalic acid addition. Mostly all iron ions in the solution are in the divalent state at Electro Motive Force (EMF) values less than 275 mV. The solubility of ferrous oxalate dihydrate was measured at different temperatures and phosphoric acid concentrations. A recovery study for oxalic acid from the precipitated FeC2O4.2H2O has performed.

Iron Speciation in Insoluble Dust from High-Latitude Snow: An X-ray Absorption Spectroscopy Study

Iron is thought to limit the biomass of phytoplankton populations in extensive regions of the ocean, which are referred to as high-nutrient low-chlorophyll (HNLC) regions. Iron speciation in soils is still poorly understood. We have investigated inorganic and organic standard substances, diluted mixtures of common Fe minerals in insoluble dust in snow from the Laohugou No.12 glacier, and sand (including soil and moraine) samples that were collected from western China. The speciation of iron (Fe) in insoluble dust and sand was determined by X-ray absorption near-edge structure (XANES) spectroscopy. A linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: Fe2O3, Fe3O4, biotite, and ferrous oxalate dihydrate (FOD). A significant altitude effect was detected for snow. The proportion of Fe2O3 in snow decreases gradually, and vice versa for FOD. As for Fe3O4 and biotite, the altitude effect was also detected, but separate regions should be considered to be deduced by topography. The Fe species in moraines and soils were also analyzed to identify the source of moraines and the heterogeneity of soils, and were compared with snow.

Innovative findings about ferrous oxalate dihydrate crystallization in simulated dihydrate phosphoric acid product

The basic fundamentals of ferrous oxalate dihydrate (FeC2O4.2H2O) crystallization including supersaturation, nucleation and crystal growth in simulated dihydrate phosphoric acid product with and without cetyl pyridinium chloride (CPC) additive were studied. Oxalic acid and ferrous sulfate heptahydrate crystals were mixed with dilute phosphoric acid (28% P2O5) at 60 °C and the turbidity of the reaction mixture was measured at different time intervals. Induction time of ferrous oxalate dihydrate crystals was calculated at different supersaturation ratios ranging from 2.5 to 6.7. With increasing the supersaturation ratio, the induction time decreased. The nucleation rates are 46.4 × 1028 nuclei cm-3 s-1 and 50.2 × 1028 nuclei cm-3 s-1 at supersaturation ratio 6.7 with and without CPC addition, respectively. The surface energy increases with CPC addition compared to the baseline. In addition, the formed crystals are modified from cubic shape to rod-like shape with increasing CPC dose.

Degradation of the cyanotoxin microcystin-LR using iron-based photocatalysts under visible light illumination.

In this study, a simple and low-cost method to synthesize iron(III) oxide nanopowders in large quantity was successfully developed for the photocatalytic degradation of microcystin-LR (MC-LR). Two visible light-active iron(III) oxide samples (MG-9 calcined at 200°C for 5h and MG-11 calcined at 180°C for 16h) with a particle size of 5-20nm were prepared via thermal decomposition of ferrous oxalate dihydrate in air without any other modifications such as doping. The synthesized samples were characterized by X-ray powder diffraction, 57Fe Mössbauer spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) specific surface area analysis, and UV-visible diffuse reflectance spectroscopy. The samples exhibited similar phase composition (a mixture of α-Fe2O3 and γ-Fe2O3), particle size distribution (5-20nm), particle morphology, and degree of agglomeration, but different specific surface areas (234m2g-1 for MG-9 and 207m2g-1 for MG-11). The results confirmed higher photocatalytic activity of the catalyst with higher specific surface area. The highest photocatalytic activity of the sample to decompose MC-LR was observed at solution pH of 3.0 and catalyst loading of 0.5gL-1 due to large amount of MC-LR adsorption, but a little iron dissolution of 0.0065wt% was observed. However, no iron leaching was observed at pH5.8 even though the overall MC-LR removal was slightly lower than at pH3.0. Thus, the pH5.8 could be an appropriate operating condition for the catalyst to avoid problems of iron contamination by the catalyst. Moreover, magnetic behavior of γ-Fe2O3 gives a possibility for an easy separation of the catalyst particles after their use.

The enhanced MR performance of dimorphic MR suspensions containing either magnetic rods or their non-magnetic analogs

A co-precipitation method was used to prepare non-magnetic rod-like ferrous oxalate dihydrate (Fe2CO4 · 2H2O) particles that were further turned into iron oxide (Fe3O4) magnetic rod-like particles. A simple precursor-assisted thermal decomposition technique enabled the preservation of the morphology and size of the precursor ferrous oxalate dihydrate particles, thus allowing their magnetic analogs to be obtained. Both types of rod-like particles were used as an additive together with spherical carbonyl iron (CI) particles in novel dimorphic magnetorheological (MR) suspensions. Controlled shear rate mode experiments were performed using a rotational rheometer with a source of an external magnetic field in order to investigate their MR behavior. Moreover, the properties of the novel prepared dimorphic MR (DMR) suspensions were compared with conventional MR suspensions based on spherical CI microparticles. It was found that the DMR suspensions exhibit enhanced MR performance as well as enhanced sedimentation stability in comparison with the MR suspension based on pure CI. The dimorphic suspensions containing magnetic rod-like additives further exhibited significant MR hardening at low shear rates. The properties of CI-based suspensions can be thus optimized by using various additive substances.

Crystalline-selected synthesis of ferrous oxalate dihydrate from spent pickle liquor

Ferrous oxalate dihydrate with different crystalline structures, polymorphs and sizes have been synthesized through a facile precipitation reaction from spent pickling liquors (SPL) by controlling synthesis conditions. The β-FeC2 O4 · 2H2 O in orthorhombic phase can be formed at room temperature, whereas α-FeC2 O4 · 2H2 O with a monoclinic unit cell can be obtained after aging at 80 °C. With the increasing aging temperature, the morphology of samples can be tailored from flower-like to prismatic-like and the particle-sizes are decreased. Innovatively, thermal decomposition behaviors of products have been investigated in details by X-ray diffraction pattern (XRD) and thermal gravimetric-differential scanning calorimetry (TG-DSC). The results show that both FeC2 O4 · 2H2 O samples can be transformed to α-Fe2 O3 in air atmosphere and Fe3 O4 in argon atmosphere at T ≧ 400 °C. In air atmosphere, there are two sharp exothermic peaks for β-FeC2 O4 · 2H2 O (250 °C) and α-FeC2 O4 · 2H2 O (239.5 °C) correspond to the decomposition reactions. In argon atmosphere, the decomposition end temperatures are 500 °C and 430 °C for β-FeC2O4 · 2H2O and α-FeC2O4 · 2H2O, respectively. This indicates that β-FeC2O4 · 2H2O has higher thermal stability in comparison with α-FeC2O4 · 2H2O.

“Physicochemical processing of low grade ferruginous manganese ores”

This study is focused on the develop of a cost effective physicochemical beneficiation process for low grade ferruginous manganese ores to recover a valuable iron bearing by-product (Fe Oxalate or Mn Ferrite) and manganese ore concentrate. It was found the one molarity solution of oxalic acid can leach five times more Fe than Mn from ferruginous manganese ores during treatment at temperature 333 K for 2 h. Photoreduction of the leached solution with sunlight for four hours provided ferrous oxalate dihydrate of >75 % purity which was further converted into Mn ferrite by roasting it at 773 K for 4 h. Residue samples were roasted in a controlled atmosphere tubular furnace (temperature: 573 - 973 K; time: 1, 3, 5 h) and muffle furnace (temperature: 523- 773 K; time: 2, 4, 12 h) to study the formation of maghemite coating on the surface of iron bearing particles. Chemical analysis, XRD, SEM, magnetometer tests were carried out to characterize the products recovered at different stages of the process. Davis tube magnetic separation tests were conducted using different current intensity (0.5, 1, 2 A) to establish grade and yield of the ore concentrate. The proposed process can recover 0.12-0.25 tons of iron oxalate and 0.33-0.50 tons of manganese ore concentrate (Mn: 42-55 % and Mn/Fe: 2.91-4.5) by processing of one ton of low grade ferruginous manganese ore (Mn: 19.3-31.3 % and Mn/Fe: 0.48-1.16).

The glassy behaviour of poorly crystalline Fe2O3 nanorods obtained by thermal decomposition of ferrous oxalate

Nanorod ferrous oxalate dihydrate (FeC2O4 × 2H2O) which had been synthesized by the microemulsion method, was used as a precursor in the thermal decomposition process performed in air atmosphere. The formation of nanocrystalline hematite as the final product was preceded by the appearence of an intermediate product. Comprehensive study comprising several complementary techniques (x-ray diffraction, transmission electron microscopy, selected area electron diffraction, thermogravimetric/differential thermal analyses and SQUID magnetometry) confirmed that the intermediate product corresponds to the poorly crystalline Fe2O3. Due to the specific nanorod shape and poorly crystalline structure, the investigated Fe2O3 showed high coercive field value of at Special attention in this study was devoted to the peculiar magnetic properties of poorly crystalline Fe2O3, which were thoroughly investigated by employing sophisticated experimental procedures such as relaxation of thermoremanent magnetization for different cooling fields, zero field and field cooled memory effects as well as aging experiments for different waiting times. At low temperatures and weak applied magnetic fields, the investigated system behaves similarly to spin glasses, manifesting slow, collective relaxation dynamics of magnetic moments through memory, rejuvenation and aging effects.

Kinetic Modeling for Thermal Dehydration of Ferrous Oxalate Dihydrate Polymorphs: A Combined Model for Induction Period–Surface Reaction–Phase Boundary Reaction

In this study, ferrous oxalate dihydrate polymorph particles, α- and β-phases, with square bipyramidal and quadratic prismatic shapes, respectively, were synthesized. Thermal dehydration of the samples was subjected to kinetic study as a typical reaction that indicates a significant induction period and a sigmoidal mass-loss behavior. On the basis of the formal kinetic analysis of the mass-loss traces recorded under isothermal, nonisothermal, and constant transformation rate conditions and the morphological observations of the surface textures of the partially reacted sample particles, a combined kinetic model for the induction period-surface reaction-phase boundary reaction was developed. The sigmoidal mass-loss behavior after the significant induction period under isothermal conditions was satisfactorily simulated by the combined kinetic model. The kinetic parameters for the component processes of induction period, surface reaction, and phase boundary reaction were separately determined from the kinetic simulation. The differences in the kinetic behaviors of the induction period and the phase boundary reaction between α- and β-phase samples were well described by the kinetic parameters. The applicability of the combined kinetic model to practical systems was demonstrated through characterizing the physicogeometrical kinetics of the thermal dehydration of ferrous oxalate dihydrate polymorphs.

Monolithic Fe2O3/graphene hybrid for highly efficient lithium storage and arsenic removal

We fabricated a monolithic Fe2O3/graphene hybrid directly by hydrothermal reaction of ferrous oxalate dihydrate and graphene oxide without using a reducing agent. The reduced graphene oxide formed an interconnected network structure that can be used as a support for homogeneous distribution of active Fe2O3 nanoparticles. The graphene network and the pore channels in the hybrid facilitate fast electron transfer and ion transport. This hybrid can be directly used as a free-standing anode for lithium ion batteries, which simplifies the fabrication procedure of electrodes, and also exhibited a high capacity of 1062mAhg−1 at 100mAg−1, high rate capability and excellent cyclic stability over 100 cycles. Furthermore, as a self-supported adsorbent, it provides a new idea on loading active materials to the suitable substrate, which can be used as a promising material for water purification due to its easy collection and excellent capability in removing As(V) from water. The results demonstrate the promising applications of bulk reduced assembly of graphene with functional metal oxides, which will be helpful for future development of graphene-based multifunctional materials.

Formation and Transformation Kinetics of Amorphous Iron(III) Oxide during the Thermally Induced Transformation of Ferrous Oxalate Dihydrate in Air

Focusing on the formation and transformation of amorphous Fe(2)O(3) in the course of the thermally induced transformations of ferrous oxalate dehydrate in air, the kinetics and physico-geometric mechanisms of the respective reaction steps were investigated systematically by means of thermoanalytical methods, complemented by other techniques. The final product of α-Fe(2)O(3) is produced by heating the sample to 700 K via intermediates of poorly crystalline anhydrous FeC(2)O(4) and amorphous Fe(2)O(3), where the external shape and size of the original sample particles are retained during the overall course of reactions. The initial parts of all the three distinguished reaction steps, that is, thermal dehydration of crystalline water, oxidative decomposition of anhydrous FeC(2)O(4) and crystallization of amorphous Fe(2)O(3), are controlled kinetically by the formation or reconstruction of the surface product layers. The surface product layers play important roles of regulating the physico-geometric kinetic behavior of the established parts of the reactions. The oxidative decomposition of intermediate anhydrous FeC(2)O(4), characterized as the formation process of amorphous Fe(2)O(3), arrests in the final stage of the reaction. The as-produced amorphous Fe(2)O(3), protected probably by the outer shell of the surface product layer and the residual anhydrous FeC(2)O(3), crystallizes to α-Fe(2)O(3) being induced by the surface crystallization. Aiming to contribute notably toward provision of the establishment of the novel fabrication routes of nanosized iron oxides by the controlled crystallization of amorphous Fe(2)O(3), the possible factors controlling and/or affecting the formation and transformation kinetics of amorphous Fe(2)O(3) were discussed.